Comparative Pharmacology
Head-to-head clinical analysis: AMEN versus NORETHINDRONE AND ETHINYL ESTRADIOL 7 14.
Peer-Reviewed Evidence
Head-to-head clinical analysis: AMEN versus NORETHINDRONE AND ETHINYL ESTRADIOL 7 14.
AMEN vs NORETHINDRONE AND ETHINYL ESTRADIOL (7/14)
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Progesterone receptor agonist; induces secretory endometrium, inhibits gonadotropin release, and alters cervical mucus.
Norethindrone is a progestin that suppresses gonadotropin release, preventing ovulation. Ethinyl estradiol is an estrogen that provides negative feedback on the hypothalamic-pituitary axis, further inhibiting ovulation. The combination also alters cervical mucus and endometrial lining to impede fertilization and implantation.
Medroxyprogesterone acetate (AMEN): 5-10 mg orally once daily for 5-10 days, starting on day 16 or 21 of menstrual cycle; also 150 mg IM every 3 months for contraception.
One tablet (norethindrone 0.5 mg/ethinyl estradiol 35 mcg) orally once daily for 21 days (7 active tablets of norethindrone 0.5 mg/ethinyl estradiol 35 mcg followed by 14 active tablets of norethindrone 1 mg/ethinyl estradiol 35 mcg). Start on day 1 of menstrual cycle.
None Documented
None Documented
Terminal elimination half-life is approximately 4-6 hours. In severe hepatic impairment, half-life may be prolonged up to 12 hours.
Norethindrone: 8-11 hours; Ethinyl estradiol: 17-27 hours. Achieves steady state within 5-10 days, permitting once-daily dosing.
Primarily hepatic metabolism to inactive metabolites, with <1% excreted unchanged in urine. Fecal elimination of metabolites accounts for ~30%.
Norethindrone: ~50% renal, ~50% fecal; Ethinyl estradiol: ~50% renal, ~50% fecal, with enterohepatic circulation.
Category C
Category D/X
Progestin
Progestin